1. Field of the Invention
The present invention relates to an ink jet printer head to be used, for example, in a printer, a copying machine, or a facsimile device, as well as a method for fabricating the same. Particularly, the invention is concerned with an ink jet printer head capable of being obtained from a single substrate, as well as a method for fabricating the same.
2. Description of the Prior Art
Heretofore, various types of ink jet printer heads utilizing a shear mode of a piezoelectric material have been proposed, including the one disclosed in Japanese Unexamined Patent Publication No. Sho 63-247051. In many of them, however, as pointed out in Japanese Unexamined Patent Publication No. Hei 7-101056, fine grooves serving as pressure chambers are formed by means of a diamond blade and the piezoelectric material typified by PZT (lead zirco-titanate) is ferroelectric. For these reasons, even a portion not concerned in ink jet have a large capacitance, thus giving rise to the problem that the energy efficiency is poor.
In the method disclosed in the aforesaid Japanese Unexamined Patent Publication No. Hei 7-101056, as shown in FIG. 1, a piezoelectric member 2 and a low dielectric member 3 are joined together on a base member. Further, a top plate 4 and a nozzle plate 5 are joined together, and a large number of grooves are formed to form an ink chamber 6. The portion of each ink chamber 6 located in the piezoelectric member 2 is a portion, a, concerned with use in an ink jet, while the portion thereof located in the low dielectric member 3 is a portion, b, not concerned in ink jet. With this configuration, the capacitance of the portion, b, not taking part in operation of an ink jet in the ink chamber 6 is made low to increase the energy efficiency.
Problems involved in such conventional techniques will now be described. In Japanese Unexamined Patent Publication No. Hei 7-101056 there is disclosed nothing disclosed about means for obtaining a large number of ink jet printer heads from a single substrate and thus the technique disclosed therein is poor in mass-productivity.
Nor is there found therein any concrete disclosure about how to bond constituent members. Since electrodes are formed within grooves, if air bubbles or the like are formed in adhesive layers, the electrodes may be short-circuited with adjacent elements, or conversely the electrodes may not be connected well on the adhesive layers, which is apt to cause an accident of open circuit.
Further, in such a structure as disclosed in the foregoing Japanese Unexamined Patent Publication No. Hei 7-101056, wherein the piezoelectric member 2 which is movable and the low dielectric member 3 which is not movable are joined together, an adhesive is present in the boundary between the piezoelectric member 2 using a ceramic material or the like and the low dielectric member 3 using an alumina substrate or the like, but as known well, ceramic materials and resins are markedly different in mechanical characteristics such as Young's modulus, so if variations occur in the thickness of the adhesive, there occur variations in the deformation of the piezoelectric member 2. If the thickness of the adhesive is large, the adhesive serves as a damper and will not obstruct the deformation of the piezoelectric member 2 so greatly, but if it is too small, one end of the piezoelectric member 2 assumes a solid state and obstructs the deformation of the piezoelectric member.